Car in reverse rolls backwards when parked on 11 degree slope driveway

[Software Mechanic]

When I retrieved my 2000 Jetta TDI (296,000 miles) from my son, a long term loan, the transmission in reverse would not prevent it from rolling down the driveway (11% grade) and turning the engine. It was a fairly fast roll back, not a slow roll where the engine was straining to hold the car back. I remember reverse being able to prevent the car from rolling backwards when parked on the driveway.

A compression test showed all cylinders to be above 420 psi using an inexpensive compression tester from Amazon. Should the car roll backwards with 420 psi compression? Would a leak-down test give me useful information?

Thanks,
John

 

[oilhammer]

Your parking brake will hold the car no matter what.

 

[jettawreck]

Don't leave it in reverse.

 

[wonneber]

Get the heavier parking brake cables and clips from ID-Parts.
Install them on my old 03 JSW.
Was the easiest upgrade to do.

 

[snakeye]

I

Get the heavier parking brake cables and clips from ID-Parts.
Install them on my old 03 JSW.
Was the easiest upgrade to do.

I found them to be the most useless upgrade. Regular cables are fine and cheap, the HD ones rust out in the exact same way for double the cost.

 

[BobnOH]

11° grade is about 20%, quite steep. I would leave it in 1st, apply foot brake, set parking brake. Should stay.

 

[Nero Morg]

Definitely use a park brake. Even my 7.3idi will roll backwards in gear. Just because compression is good doesn't mean that air will seep by the rings when it's not running.

 

[DonL]

My daughter ignored my advice to leave her Sentra (manual) in gear and parking brake on. So, on the day the parking brake failed the car rolled into another car causing minor damage. This was in a mostly, but not quite, level parking lot. So simple, leave the car in gear or in park and SET the parking brake properly. Any other questions?

 

[Genesis]

On relatively flat ground I just leave a stick in REVERSE (lowest gear, thus highest mechanical force required to turn the engine.) But if on any sort of grade then the parking brake is used AND the wheels turned (preferably into a curb if there is one.) It used to be that in towns where grades were present if you didn't curb they wheels in this fashion they'd actually ticket you -- with good cause.

 

[mittzlepick]

Never trust a vw parki g brake they are ****e

 

[BobnOH]

At least here in the rusty part of the country, it's good practice to use the parking brake on all your cars. Only to keep the cables moving once in a while.

 

[oilhammer]

I use the parking brake on all my cars, every time I park, BEFORE I put the transmission in gear or Park, and it has never ever, EVER, been a problem. It isn't like a parking brake not working suddenly sneaks up on you.

 

[P2B]

It isn't like a parking brake not working suddenly sneaks up on you.

It can in the frozen north - set the parking brake on a cold day, caliper lever is slow to return when released allowing the cable end to become unhooked, all of a sudden no parking brake.

I've had it happen twice on MK4 cars, but not since fitting return springs.

 

[Andyinchville1]

For maximum safety if you worry that 1st gear and parking brake is not enough you can always curb the front wheels (if curb is available) or use good old fashioned solid rubber wheel chocks.

On many older (maybe even newer?) medium duty trucks with auto trannies and juice brakes, there was no park pawl in the tranny and the truck was only held back from rolling by the mechanical trans brake (a drum brake on the rear of the tranny). ...

I ALWAYS told the guys to chock the wheels (in front of the wheel and behind the wheel if they don't know which way is down hill because of only a minor grade) ....

We actually had 3 parking brake cable breakages and 3 truck roll aways ... each time very lucky and the cable either snapped when applied or when somebody was nearby to "catch" truck before total roll away.... wow .... it scares me just thinking about that again.

Be safe.

Andrew

 

[Genesis]

Modern disc parking brakes work quite well.

Want a nightmare? The "drum-in-hat" parking brakes on basically every GM truck made over the last 30+ years. They all suck, they do not auto-adjust and you have to TAKE THE ROTOR OFF to adjust them because there's no window on the back of the mounting plate where the star wheel is like there was on drum brake vehicles for basically all time. Which means on 90% of said trucks out there on the road it either doesn't work at all or is weak as hell and WILL NOT HOLD.

Now lose the parking pawl and.... surprise!

 

[03TDICommuter]

Modern disc parking brakes work quite well.

Want a nightmare? The "drum-in-hat" parking brakes on basically every GM truck made over the last 30+ years. They all suck, they do not auto-adjust and you have to TAKE THE ROTOR OFF to adjust them because there's no window on the back of the mounting plate where the star wheel is like there was on drum brake vehicles for basically all time. Which means on 90% of said trucks out there on the road it either doesn't work at all or is weak as hell and WILL NOT HOLD.

Now lose the parking pawl and.... surprise!

Is there an access port on the drum itself? I just adjusted the parking brakes on an 03' Kia Optima and that's how theirs was accessed.

 

[Genesis]

Is there an access port on the drum itself? I just adjusted the parking brakes on an 03' Kia Optima and that's how theirs was accessed.

Nope. On the GMs there is no way to get to the star adjuster without removing the rotor.
Which requires removing the caliper AND bracket.
This also means that each adjustment attempt you make requires replacing said rotor, checking for drag, pull it back off, make another adjustment, etc. It is a FIVE ALARM pain in the butt.

Which is why basically NOBODY ever adjusts them from the time they put new brakes on until the pads and rotors require replacement (and which means the parking brake is, on most of those vehicles at any given time, worthless.)

In addition because the parking brake mechanism is inside the hat and thus never gets hot in normal use if you live in a salted-road area the entire mechanism will turn into a ball of rust within a couple of years as it never completely dries out.

I own one of these trucks and if there is one thing I'd like to string a GM engineer up for, its this.

 

[03TDICommuter]

Nope. On the GMs there is no way to get to the star adjuster without removing the rotor.

Horrible! Our PT cruiser too has drum parking brakes inside the rotor hat but I'm pretty sure there's an access hole. Wow, GM really screwed up on that.

 

[CopaMundial]

Can't believe we're 18 posts deep into this topic an no one has pointed out that the OP is simply failing to park sideways across the incline in his driveway.
Time to practice those drifting skills.

 

[2004LB7]

Modern disc parking brakes work quite well.

Want a nightmare? The "drum-in-hat" parking brakes on basically every GM truck made over the last 30+ years. They all suck, they do not auto-adjust and you have to TAKE THE ROTOR OFF to adjust them because there's no window on the back of the mounting plate where the star wheel is like there was on drum brake vehicles for basically all time. Which means on 90% of said trucks out there on the road it either doesn't work at all or is weak as hell and WILL NOT HOLD.

Now lose the parking pawl and.... surprise!

this is not quite correct. they do have an access hole but it is such a pain to use that it is easier to remove the rotor to adjust. the hole is a small oval with a little rubber plug stuffed in it. and since they use the same parts on both side except one side is flipped upside down compared to the other the adjustment hole is affectively inaccessible.

there is a special tool that is supposed to be used but a flat blade screw driver with the tip bent at a 45° or so will work too.

this is of course speaking of experience on my 08 Duramax.

some photos here: https://www.duramaxforum.com/threads/adjusting-parking-brake.158693/

 

[Genesis]

No, the hole is worthless; the boot is there for the lever which is in the way of the adjuster, and as you note one side is upside down and thus inaccessible even if you were crazy enough to screw with it. Because of the equalizer "T" on the cable if one side does not engage then BOTH are worthless.

Oh and if you dislodge the lever from the cylinder inside while attempting to screw with it from the back you get to take the entire thing apart as there is no way to get it back in the correct place with tension on it.

I've owned cars with drum brakes and there was ALWAYS a reasonable way to get to the adjuster without disassembling it. Except for these trucks.

 

[Zak99b5]

I gave up the idea of having functional parking brakes on my Suburban.

It’s a real pain in the ass when I’m on a slope and trying to hitch up the camper by myself.

 

[Genesis]

My solution is to put the truck in 4LL if in a dicey situation when parking as that wildly increases the ratio and thus takes the stress off the "park" mechanism in the transmission. And yeah, it's a pain when hooking up a trailer single-handed as it DOES move just enough to play with you in terms of ball alignment.

 

[Zak99b5]

My Suburban will move anywhere from 1-4” after I put it in park and let my foot off the brake pedal.

Never thought about using 4 low for parking on a steeper hill. Good idea.

 

[2004LB7]

my question is, why don't they make the parking brakes with cogs in the shoes and drum? something somewhat like the transmission parking pawl. then the parking brakes wouldn't need to be so finely adjusted and would have much better holding power

 

[Wilkins]

Disk parking brakes work well????
Maybe if the disks are in perfect condition but in the last 10 years I have yet to wear out brake pads. It’s always the disk that goes first, front or rear, usually after about 2 winters. Once the disks start to go the parking brake is not enough to hold on my driveway. I see the ID4 has rear drums because of this issue

 

[KLXD]

Compression is not what holds the car on a hill when in gear, only friction. Unless it's really steep and the brake isn't set.

When you park, you set the parking brake tight enough that it's holding then put it in gear. A lot, if not most, folks give it a yank or a stomp and call it good with no thought of what it's doing and if it's tight enough.

 

[KrashDH]

Compression is not what holds the car on a hill when in gear, only friction.

Yes, compression is what keeps the vehicle stationary...if you are in gear on a hill. Which is why reverse is normally the best choice (highest gear ratio).

Curb the wheels, parking brake on, put it in reverse.

 

[Software Mechanic]

The parking brake holds the car. Before my son borrowed the car for several years, a long story, I could park it in the driveway without it rolling back. Previous compression tests showed about 500 psi in each cylinder. Unfortunately, records didn't comeback with the car. The recent compression test showed 420+ psi in each cylinder. Two days after the car was returned the transmission started to sound like it had rocks in it. I'm putting a used transmission in it and replacing the timing belt. I'm hoping to get another 50,000 miles out of it. It has been well maintained, when something needed to be fixed, he brought it over and we fixed it. I want to know if a leak down test would provide useful information.

 

[oilhammer]

You guys are funny. My camper is sitting in my sloped driveway right now, hitched to the back of my [stick shift] F150, wheels pointed straight ahead, and the whole mess is being held firmly and reliably in place with the parking brake. It won't roll. At all. I could reach in and move the gearshifter around right now, there is zero weight being placed on the transmission.

If your parking brake doesn't work, it is broken, and needs to be fixed. It isn't that big of a deal. I understand areas that get more road salt than we do will present more frequent need for servicing of ALL your brakes, but that doesn't mean you cannot drive a car.